1. Technical Field
The present disclosure relates to a disposable loading unit (“DLU”) or single use loading unit (“SULU”) for use with a surgical device. More particularly, the present disclosure relates to a DLU or SULU for use with a surgical instrument which includes a locking mechanism for retaining a drive assembly of the loading unit in its prefired position until the loading unit is attached to a surgical device. For simplicity, hereinafter, SULU or DLU will be referred to as “DLU”, but it should be understood to include either or both a DLU or SULU.
2. Background of Related Art
Surgical devices for applying fasteners, e.g., staples, clips, etc., to tissue are well known. Such devices include single use devices which are preloaded with a single fastener and are disposable after a single use of the device. Such devices also include multiple use devices which are preloaded with a plurality of fasteners and are disposable after the supply of fasteners has been exhausted or a surgical procedure has been completed. If the supply of fasteners is exhausted prior to completion of a surgical procedure, a new device may be required to complete the surgical procedure. The use of additional surgical devices for a single surgical procedure can be expensive.
In order to address the high expense of using multiple surgical devices for a single procedure, surgical devices having replaceable fastener cartridges have been developed. In such devices, fasteners are housed within a cartridge. When the fasteners in the cartridge have been exhausted, the cartridge can be removed from the surgical device and replaced with a new cartridge having an additional supply of fasteners.
Tyco Healthcare Group, LP, the assignee of the present application, has manufactured and marketed endoscopic stapling devices having replaceable cartridges, such as the Multifire ENDO GIA™ 30 and Multifire ENDO GIA™ 60 devices, for a number of years. These devices include a surgical stapling apparatus and a DLU. Typically, the DLU includes a proximal body portion and a distal tool member and is attached to a surgical apparatus immediately prior to surgery. The distal tool member includes a cartridge housing a plurality of staples. After use, the DLU can be removed from the apparatus and replaced with a new DLU to perform additional stapling and/or cutting operations. A drive assembly is supported within the DLU and is engageable with a control rod of the surgical apparatus to facilitate operation of the apparatus.
Although, these devices have provided significant clinical benefits, improvements to these devices are still possible. Accordingly, it would be desirable to provide an improved DLU for a surgical fastener applying device which retains or locks the DLU drive assembly in a prefired position until the DLU is attached to the surgical fastener applying device.